Combination square sets are commonplace tools traditionally used in woodworking, stonemasonry and metalworking. These sets are usually composed of a ruled blade and three interchangeable moving heads: a 45°/90° square head, a protractor head and center gradation head. These moving heads can slide along the ruled blade, and be clamped onto the blade at any desired location. By removing all of these heads, the blade can be used by itself as a standard ruler or as a straight edge.
The square head is designed with a 45° and also a 90° edge, which makes it possible for it to be used as a “try square” (i.e. a tool used for reliably measuring straight angles) and also as a “miter joint square” (i.e. a joint created by beveling two parts to be joined). The square head is also typically fitted with a level and a removable gradation scriber.
The combination square set can further be used for determining flatness (relative to a flat surface), measuring and setting angles between a base and the ruler (with the protractor), approximating leveled surfaces (with a rudimentary level), and gradation the work surface (with the scriber). The protractor head can be used to mark off or measure any angle from 0° to 180° (permitting the supplement of the angle to be read).
Thus, such a combination square set can provide a wide variety of operations and uses; however it also obliges the operator to carry three separate heads together with the ruler, since none of the heads can be used while a different head is mounted onto the blade. It will therefore be advantageous to provide a single compact combination square apparatus that can provide all possible operations of the combination square set, without requiring changing heads.